AP Power Saving Date: 2017-05-08 Authors: May 2017 Month Year doc.: IEEE 802.11-yy/0728r0 May 2017 AP Power Saving Date: 2017-05-08 Authors: Xiaofei Wang (InterDigital) John Doe, Some Company

May 2015 doc.: IEEE 802.11-15/0728r0 May 2017 Abstract In this contribution, we provide simulation results of AP power saving and discuss the benefits of AP power saving. Xiaofei Wang (InterDigital) Xiaofei Wang (InterDigital)

May 2015 doc.: IEEE 802.11-15/0728r0 Introduction May 2017 Multiple usage scenarios have been proposed that involve mobile[1] UM 3: Cattle farm UM 5 & 6: Wearable devices Power consumption is a very important issue for mobile AP Mobile APs could be cell phones or ad hoc deployed devices operating on batteries without power plugs Power saving prolongs network lifetime; improves user experience Other benefits: regulatory, interference, security, etc. In this contribution, we provide simulation results on power savings for AP based on a number of scenarios AP power saving with varying duty cycles for AP’s PCR Xiaofei Wang (InterDigital) Xiaofei Wang (InterDigital)

AP Power Saving Scenarios (1) May 2015 doc.: IEEE 802.11-15/0728r0 AP Power Saving Scenarios (1) May 2017 Scenario 1: AP’s PCR is always on, i.e., duty cycle 1 PCR beacons: BI: 100 ms Size: 100 bytes TX MCS: 1 Mbps/6.5 Mbps WUR beacons: BI: 10s TX duration: 144 us [2] UL data only; STA behavior: transmit data to AP directly when data arrives; No need for UL WUR packet from STA to AP AP power consumption is simulated Xiaofei Wang (InterDigital) Xiaofei Wang (InterDigital)

AP Power Saving Scenarios (2) May 2015 doc.: IEEE 802.11-15/0728r0 AP Power Saving Scenarios (2) May 2017 Scenario 2: AP’s PCR is on duty cycle 1/2 PCR beacons: BI: 100 ms Size: 100 bytes TX MCS: 1 Mbps/6.5 Mbps WUR beacons: BI: 10s TX duration: 144 us [2] AP’s PCR duty cycle: of ½; UL data only; STA behavior: STA transmits PCR packet directly when AP is awake. Otherwise STA sends WUP to AP followed by PCR packet exch. AP’s WUR is always on except when PCR is on AP power consumption is simulated Xiaofei Wang (InterDigital) Xiaofei Wang (InterDigital)

AP Power Saving Scenarios (3) May 2015 doc.: IEEE 802.11-15/0728r0 AP Power Saving Scenarios (3) May 2017 Scenario 3: AP’s PCR is on duty cycle 1/4 PCR beacons: BI: 100 ms Size: 100 bytes TX MCS: 1 Mbps/6.5 Mbps WUR beacons: BI: 10s TX duration: 144 us [2] AP’s PCR duty cycle: of 1/4; UL data only; STA behavior: STA transmits PCR packet directly when AP is awake. Otherwise STA sends WUP to AP followed by PCR packet exch. AP’s WUR is always on except when PCR is on AP power consumption is simulated Xiaofei Wang (InterDigital) Xiaofei Wang (InterDigital)

AP Power Saving Scenarios (4) May 2015 doc.: IEEE 802.11-15/0728r0 AP Power Saving Scenarios (4) May 2017 Scenario 4: AP’s PCR is always off except when being woken up or sending beacons PCR beacons: BI: 100 ms Size: 100 bytes TX MCS: 1 Mbps/6.5 Mbps WUR beacons: BI: 10s TX duration: 144 us [2] AP’s PCR is off except when: 1)Transmitting beacon; 2)When woken up by a STA; AP’s WUR is always on except when PCR is on STA behavior: When having data, always send a WUP to wake up AP before continuing on with PCR packet exchanges Xiaofei Wang (InterDigital) Xiaofei Wang (InterDigital)

Simulation Assumptions (1/2) May 2015 doc.: IEEE 802.11-15/0728r0 Simulation Assumptions (1/2) May 2017 Matlab Simulations Simulation time: 100s Usage Model 3: Cattle farm: 1 farmer (Mobile AP) 30/50 cows (STAs) Traffic Assumptions: UL data only Packet arrival interval per STA: [5:5:50] s Packet size: 32 bytes AP PCR Duty cycle: [1, ½, 1/4, 0] AP Power Consumptions simulated Xiaofei Wang (InterDigital) Xiaofei Wang (InterDigital)

Simulation Assumptions (2/2) May 2015 doc.: IEEE 802.11-15/0728r0 Simulation Assumptions (2/2) May 2017 Xiaofei Wang (InterDigital) Xiaofei Wang (InterDigital)

Simulation Results (1/4) May 2015 doc.: IEEE 802.11-15/0728r0 Simulation Results (1/4) May 2017 Xiaofei Wang (InterDigital) Xiaofei Wang (InterDigital)

Simulation Results (2/4) May 2015 doc.: IEEE 802.11-15/0728r0 Simulation Results (2/4) May 2017 Xiaofei Wang (InterDigital) Xiaofei Wang (InterDigital)

Simulation Results (3/4) May 2015 doc.: IEEE 802.11-15/0728r0 Simulation Results (3/4) May 2017 Xiaofei Wang (InterDigital) Xiaofei Wang (InterDigital)

Simulation Results (4/4) May 2015 doc.: IEEE 802.11-15/0728r0 Simulation Results (4/4) May 2017 Xiaofei Wang (InterDigital) Xiaofei Wang (InterDigital)

Observations Impact by AP’s PCR Duty Cycle May 2015 doc.: IEEE 802.11-15/0728r0 Observations May 2017 Impact by AP’s PCR Duty Cycle In all scenarios with DC < 1, significant power saving is achieved When AP’s PCR’s DC = ½, AP’s power consumption is slightly higher than 50% of that when AP’s PCR’s DC = 1 When AP’s PCR’s DC = 1/4, AP’s power consumption is slightly higher than 25% of that when AP’s PCR’s DC = 1 When AP’s PCR’s DC = 0, AP’s power consumption is around 1.2% - 5.2% (depending on PCR beacon rate) of that when AP’s PCR’s DC = 1 Impact by Packet Arrival Rate Small impact when packet arrival interval increase 5 -> 50s except when DC = 0 Impact by Number of STAs No significant impact when the number of STAs is increased from 30 to 50 Impact by PCR Beacon Tx Rate Only significant when AP PCR DC = 0 Xiaofei Wang (InterDigital) Xiaofei Wang (InterDigital)

When is AP Power Saving Desirable May 2015 doc.: IEEE 802.11-15/0728r0 May 2017 When is AP Power Saving Desirable When aggregated traffic in the entire network is low It is suitable for some number of IoT usage models and scenarios However, power saving and network lifetime may be critical in these scenarios Wake up AP procedure may enable low latency while maintaining low power consumptions Latency can also be critical for some of the IoT scenarios where power saving is critical as well It may not be appropriate if: A large number of active STAs present in the BSS Traffic load is heavy in the BSS Xiaofei Wang (InterDigital) Xiaofei Wang (InterDigital)

Technical changes needed for AP Power May 2015 doc.: IEEE 802.11-15/0728r0 May 2017 Technical changes needed for AP Power An AP power saving mode: Only when scenario is appropriate E.g., AP delivered together with a cattle monitoring sensor network Only when all STAs associated with it are capable of handling AP power saving Indicated by capability An AP power saving mode with these restrictions should not violate the PAR Cost, e.g.: A low-cost WUR receiver at AP Procedure for going into power saving for APs of which all associated STAs have indicated of capable of handling AP Power Saving A wake up procedure for AP AP Discovery process Xiaofei Wang (InterDigital) Xiaofei Wang (InterDigital)

May 2015 doc.: IEEE 802.11-15/0728r0 Conclusions May 2017 An AP Power Save feature may enable critical functionalities for some IoT scenarios Allow long period of low power operation of its BSS while maintaining low latency for APs that are operated on battery power Simulation shows that AP power save provides significant energy saving benefits even with PCR DC = ½. With DC = 0, AP’s consumption could be as low as 1.2% of that when DC = 0 802.11ba should consider to optionally put 11ba APs to power saving mode when a certain set of restrictions are met Xiaofei Wang (InterDigital) Xiaofei Wang (InterDigital)

References [1] 11-17/0029r5, WUR Usage Model Document, Mar. 2017 May 2017 References [1] 11-17/0029r5, WUR Usage Model Document, Mar. 2017 [2] 11-17/0343r3, WUR Beacon, Mar. 2017 [3] 11-17/0124r1, WUR MAC and Wakeup Frame, Jan. 2017 [4] 11-16/1400r0, Power Efficient WUR AP Discovery, Nov. 2016 [5] 11-16/0029r4, WUR Usage Model Document, Jan. 2017 Xiaofei Wang (InterDigital)

Straw Poll Do you agree to add to the 802.11ba SFD May 2015 doc.: IEEE 802.11-15/0728r0 May 2017 Straw Poll Do you agree to add to the 802.11ba SFD “802.11ba shall consider an option for AP to go into power saving mode by turning off its PCR when certain criteria are met.” Xiaofei Wang (InterDigital) Xiaofei Wang (InterDigital)